1. Field of Invention
The present invention relates generally to laser scanning bar code symbol reading systems, and more particularly to portable bar code symbol reading systems capable of generating raster-type laser scanning patterns having variable speed and resolution for reading various types of 1-D and 2-D bar code symbols during hands-on and hands-free modes of operation.
2. Brief Description of the Prior Art
Bar code symbols have become widely used in many commercial environments such as, for example, point-of-sale (POS) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. To meet the growing demands of this recent technological innovation, bar code symbol readers of various types have been developed for scanning and decoding bar code symbol patterns and producing symbol character data for use as input in automated data processing systems.
In general, laser scanning bar code symbol scanners are used for reading one-dimensional (1D) and two-dimensional (2-D) bar code symbols on products and packages for identification purposes. 2-D bar code symbols are advantageous in that they have the capacity to encode a substantially larger volume of data than 1D bar code symbols. Consequently, 2-D bar code symbols have enjoyed increasing popularity over recent years.
Many different techniques exist for scanning laser beams across objects bearing 2-D bar code symbols. Examples of 2-D laser scanning mechanisms for reading 2-D bar code symbols (e.g. the popular PDF 417 symbology) are described in U.S. Pat. Nos. 5,665,954, 5,691,834, and 5,550,367 and EPO Patent Application Publication No. EP 0 731 417 A2, incorporated herein by reference.
While each of these prior art laser scanning mechanisms are capable of producing a raster-type laser scanning pattern, such prior art techniques are unnecessarily complicated, expensive to manufacture, and generally do not enable precise speed/resolution control within the raster scanning pattern in a simple and practical manner required by numerous 2-D scanning applications.
Thus, there is a great need in the bar code symbol reading art for a bar code symbol reading system and method which overcomes the above-described shortcomings and drawbacks without compromising system performance and versatility.